First I am going to adress the origional question,I would suggest crawling under your jeep and looking at the tag on your diff cover , that will tell you if it uses sythetic or not. second I am pretty sure your transfer case and trans both use mopar 4 trans fluid, I know they use tranny fluid but wether or not it is that type i am not sure. one thing is certain if it calls for special fluid use it. they do that for a reason. newer transmissions and such are built different than what they was for better fuel economy,or performance. Amsoil does make a multi use trans fluid as well that can be used in all transmissions and transfer cases.other companies make it as well.
now on to the war over synt vs regular. sythetic oil is purely man made not one drop of crude was used to make it.
sythetic blend is the combo of both and we all know regular oil is from crude oil
now on to the benifits
sythetic does not loose its viscosity as quickly hence the 5k+ oil changes thus it is cheaper in the long run if you go by the 3 k 3 month oil change rule used by reg oil. we charge 26 dollars for a regular oil change that is 5 qts with a common filter and 46 for syth with 5 qts common filter. now if you change regular oil every 3 k that is a total of 52 dollars vs 46 on sythetic.that is if you change the sythetic at 6k, alot of our customers go futher.
Another thing about sythetic as was said before it is less effected by the weather.
Bj I know for years you always said use what the manufacturer puts in in the first place, they do it for a reason. wether it is a spark plug air filter or whatever, the same gois for oil. if it calls for a certain weight ,brand,or type use it.
Personally I use a fram filter on both the wifes and my vehicle and amsoil 5w30 in hers and rotella 15w40 in my jeep. I use the sythetic in hers because we bought it new and it needs to last a long time, plus i get a discount where i buy it. i use rotella 15 w 40 because the jeep was abused it is worn and leaks. and i get that at a discount as well. Once I get my new Vehicle I will use sythetic in that as well.
